The invention relates to a method of producing a weapon barrel having a wear-resistant inner coating, applied by an electrolytic process, to the region of the chamber and of the adjoining, thermally highly-stressed caliber portion of the weapon barrel.
To achieve an improved service life of weapon barrels, it is known to provide same with a protective layer or coating. Electrolytically-applied chromium has proven particularly effective as a protective layer or coating, although other materials, such as nickel, cadmium and silver, likewise are used as a protective layer.
U.S. Pat. No. 2,395,044, for example, discloses a weapon barrel in which the chamber and the region of the initial caliber portion adjoining the chamber are coated with a chromium layer to reduce erosion. In this instance, the layer or coating thickness of the chromium in the region of the chamber is within a size range of approximately 10 .mu.m, and decreases toward the muzzle of the gun barrel.
However, in large-caliber barrels, e.g. in weapon barrels having a caliber of 155 mm, such small thicknesses of the protective layer in the region of the chamber do not effect a sufficient improvement in service life over uncoated weapon barrels. Rather, it has been found that, in this type of weapon barrel, layer thicknesses in the order of magnitude of 100-200 .mu.m are necessary. However, up to now the electrolytic application of appropriate layer thicknesses has required expensive and/or complex mechanical pretreatment and after treatment of the weapon barrel.
Furthermore, a weapon barrel provided with a protective layer is known from U.S. Pat. No. 2,687,591. In this case, the thickness of the protective layer increases toward the muzzle. Such weapon barrels have not performed well, at least in large-caliber barrels, because the highest thermal stresses of the weapon barrel occur at the inlet to the caliber portion of the barrel, i.e. at the transition from the cartridge chamber to the rifling grooves, and the protective layer must also be the thickest in this region. Moreover, experiments performed by Applicant have revealed that the protective layer or coating is frequently destroyed in the forward region of the weapon barrel because of the severe mechanical stresses, and these locations then lead to gas leakage and turbulence, which in turn can be conducive to erosion.
Finally, a weapon barrel for machine guns is known from German laid open patent application No. DE-OS 2 045 738 in which a protective layer or coating of the weapon barrel is omitted, and instead at least two exchangeable, wear-resistant bushings are used in the region under the highest thermal stress (chamber and initial caliber region of the barrel). The use of such bushings is relatively costly, because corresponding pre-turned and gas-tight fixings for the bushings must be provided in the weapon barrel. Use of this type of bushing in large-caliber weapon barrels has therefore not been generally accepted.
It is therefore an object of the present invention to disclose a method of producing a weapon barrel provided with a protective layer which is simple to produce and which withstands the high thermal stresses in the region of the chamber and of the initial caliber portion, particularly also in large-caliber weapon barrels.